Various proposals have been put forth in the past for wet-blasting techniques in which a “wet blast” is jetted onto a workpiece from a jetting part, the wet blast being formed by pressurizing with pressurized air a slurry formed of a mixture of an abrasive and a liquid, and machining such as burr processing or an abrasion test or the like is performed on a workpiece using the wet blast. Various nozzle bodies for satisfactorily jetting the wet blast have also been proposed.
In order to uniformly machine the surface of a large workpiece having, for example, a width of 600 mm or the like using a wet-blast technique, means is adopted for preparing a nozzle body for wet-blasting in which the jetting part of the nozzle body is formed in a slit shape having a width of 600 mm or greater, the workpiece is moved relative to the nozzle body, and machining is thereby performed over the entire surface of the workpiece as simultaneously as possible.
However, jetting a wet blast in a uniformly mixed state from the slit-shaped jetting part having such a prescribed width is very troublesome. This is because as the width of the jetting part increases, the concentration of abrasive in the slurry tends to increase and decrease by location.
In response, the present applicants have proposed the nozzle body disclosed in Japanese Patent No. 3540713 (hereinafter referred to as the “conventional art example”).
This conventional art example is a nozzle body in which: a slurry-accumulating chamber having a prescribed length is provided, a slurry formed of a mixture of an abrasive and a liquid being introduced into the slurry-accumulating chamber, and the slurry-accumulating chamber accumulating the slurry; an air-jetting passage having a prescribed length is provided near the slurry-accumulating chamber in a direction perpendicular to a lengthwise direction of the slurry-accumulating chamber; the air-jetting passage and the slurry-accumulating chamber are in communication through an output passage; pressurized air passes through the air-jetting passage, and the slurry is thereby outputted from the slurry-accumulating chamber via the output passage; the slurry and the pressurized air are mixed in a mixing chamber; and jetting material formed by mixing the pressurized air and the slurry is jetted from a slit-shaped jetting part. The air-jetting passage and the output passage each have a structure in which small holes are arranged side-by-side, and in this conventional art example, the abrasive, liquid, and pressurized air jetted from the jetting part at a prescribed width can be uniformly mixed.